Hack saw blade



Patented July 7, 1942 HACK SAW BLADE William H.' Shortell,Greenfield,-and Leslie D.

Hawkri'dge, Newton, Mass, assignors of onehalf to Millers Falls Company,

Mass, a corporationof Massachusetts, and onehalf toHawkridgeBrothersCompany, Boston, Mass, a corporation ofMassachusetts No Drawing.

Application August 30, 1938,

Serial No. 227,529

11 Claims.

This invention relates to hack-saw blades, and more particularly to hacksaw blades of a new composition of steel and havingvarious'useful newcharacteristics.

This invention. represents certain improvements and further discoveriesrelating to the" subject-matter of ourco-pending application, Serial No.139,434, filed April 28, 1937.

The primary object of the invention is to provide a hack saw bladehaving the combined characteristics of hardness and toughness.

Another object of the invention'is to provide a hack saw blade capableof use with equal facility on both bar and sheet metal, whether themetal is hard or soft.

Further objects and advantages of the invention will in part beobvious'and will inpart ap-- pear from the following description,wherein all specific examples and figures are to be construedi asillustrative only, and the scope ofapplication of the invention will beindicated inthe claims.

Blades constructed in accordance withthis invention have been found tohave a combination of qualities and characteristics never before wouldstrip itsteeth or break if used on sheet metal. On the other hand, ablade tempered for toughness for cutting sheet metal would be useless onharder materials. Among the at-- tempted solutions to the problem werealso blades with hard teeth tempered on a softer, tougher back. Theblades of this invention, however, are of even temper throughout, andhave such combined qualities of hardness, toughness and flexibility thatthey can be used with equally great facility and efilciency' on hard orsoft metals in either bar or sheet form.

In our above identified co-pending application, the explanation wasadvanced that the above results are due in some way to some specialqualities imparted to the alloy by the molybdenum in the particularproportions in which it is combined with the carbon and manganesecontent. Recent further research, however, make it appear that thisexplanation was not sufliciently broad, since equivalent results havenow been obtained without the use of molybdenum.

In accordance with the practice of the present invention, it has beendiscovered that various 65 other elements may be substituted in whole orin part for the molybdenum content disclosed in our said copendingapplication. It appears, therefore, that the special qualitiespossessedby the blades of the invention result primarily from the use ofcarbon in hypo-eutectoid proportions combined with relatively highmanganese content and with another element which will com bine withcarbon rather than go into solution in the ferrite, the wholecombination being in balanced proportions. Among the elements foundsuitable are vanadium, tungsten and chromium. Any one of the three maybe used alone, or either vanadium or tungsten may be combined with asuitable amount of chromium.

Accordingly, the following tables are given as examples of the generalrange of percentages of components of alloys suitable for the practiceof the invention:

Example 1 Per cent Carbon .50-l.00 Manganese .50-1.50 Silicon .10 .50Molybdenum .50-li50 Chromium (optional) .10- .50

Ewample 2 Per cent Carbon .50 -l'.00 Manganese .50-1150' Silicon.10--.5'0' Vanadium .25'1;0(l Chromium (optional) .1'0- .50'

Example 3 Per cent- Carbon .50'-l.00

Manganese .50'1.50 Silicon. .10- .50:

Tungsten .50-3100 Chromium (optional) h .10-'- .50

Example 4 Per cent Carbon .50-1.00

Manganese .50-1.50 Silicon .10- .50 Chromium .25-3.00

The remainder of the alloy in each case is essentially iron plus theusual small quantities of phosphorus and sulphur ranging downwards fromabout .02% for each element.

As typical specific illustrations, the blades of the invention may becomposed of steels having the following analyses:

Example 1 Per cent Carbon .73 Manganese .70 Silicon .24

Phosphorus .018 Sulphur .019 Vanadium .63

Example 2 Per cent Carbon .68

Manganese .72 Silicon .24

Phosphorus .016 Sulphur .018 Tungsten 1.55

The process of manufacture of the blades of this invention issubstantially conventional. The body of the blade is made by shearingand blanking from sheets of the proper gauge, which are first formed byrolling, hammering, or other suitable operation from an ingot of steelhaving a suitable analysis such as one of the examples listed above. Theteeth are formed in the usual or any suitable way, and the blade is thenheat treated in order to harden it.

It has been discovered that in the manufacture of blades according tothis invention, this hardening process is most important and must becarried on at a very limited temperature range. The ideal temperatureappears to be in the neighborhood of 1510 F. and should not be allowedto vary to an appreciable extent from this figure if the combinedqualities of toughness and cutting efficiency are to be achieved in thefinished blade. Thus if the blades are heated above about 1550 F., theywill cut satisfactorily but will be lacking in toughness. On the otherband, should they be heated only to about 1470 F., they will have thetoughness characteristic of the product of this invention but will belacking in cutting efiiciency.

It will be understood that the invention is not limited, necessarily, tothe specific details herein illustrated and described, but it will beapparent that such details are subject to various modifications whichbecome apparent readily to one skilled in the art, without departingfrom the spirit of the invention; and it will be understood, therefore,that it is intended and desired to include within the scope of theinvention such modifications and changes as may be necessary to adapt itto varying conditions and uses.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. As a new article of manufacture, a hack saw blade composed of steelcontaining .6l1.00% carbon, .50-1.50% manganese, .10-.50% silicon, and.50-3.00% tungsten, the remainder being essentially iron.

2. As a new article of manufacture, a hack saw blade composed of steelcontaining .61-1.00% carbon, .50-1.50% manganese, .l0.50% silicon and.251.00% vanadium, the remainder being essentially iron.

3. As a new article of manufacture, a hack saw blade composed of steelcontaining .6l-l.00% carbon, .50-1.50% manganese, .10-.50% silicon, and.253.00% chromium, the remainder being essentially iron.

4. As a new article of manufacture, a hack saw blade composed of steelcontaining .6l-1.00% carbon, .50-1.50% manganese, .10-.50% silicon, and.50-1.50% molybdenum, the remainder being essentially iron.

5. As a new article of manufacture, a hack saw blade composed of steelcontaining .611.00% carbon, .50-1.50% manganese, .10-.50% silicon, .50-1.00% molybdenum and .10-.50% chromium, the remainder being essentiallyiron.

6. As a new article of manufacture, a hack saw blade composed of steelcontaining .611.00% carbon, .50-1.50% manganese, .10-.50% silicon, .50-3.00% tungsten, and .10-.50% chromium, the remainder being essentiallyiron.

7. As a new article of manufacture, a hack saw blade composed of steelcontaining .6l-1.00% carbon, .50-1.50% manganese, .l0.50% silicon, .25-1.00% vanadium, and .10.50% chromium, the remainder being essentiallyiron.

8. As a new article of manufacture, a hack saw blade composed of steelcontaining approximately .75% carbon, .'70% manganese, 24% silicon, and.63% vanadium, the remainder being substantially iron with lowpercentages of phosphorus and sulphur.

9. As a new article of manufacture, a hack saw blade composed of steelcontaining approximately .68% carbon, .72% manganese, 23% silicon, and1.55% tungsten, the remainder being substantially iron with lowpercentages of phosphorus and sulphur.

10. As a new article of manufacture, a hack saw blade composed of steelcontaining .65-.70% carbon, .80-.90% manganese, .75-.85% molybdenum, andapproximately 25% silicon, the remainder essentially iron.

11. As a new article of manufacture, a hack saw blade composed of steelcontaining .611.00% carbon, .50-1.50% manganese, .l0.50% silicon, andthe following elements: molybdenum, tungsten, vanadium, and chromium, toa total quantity of .501.80%, the remainder being essentially llOl'l.

WILLIAM H. SHORTELL. LESLIE D. HAWKRIDGE.

